The Open Door Web Site
Part XX: How Organisms Communicate
The Effect of Stimuli on the Behaviour of an organism
The tentacles of jellyfish are organs of touch
The lateral line is able to sense differences in the
TOUCH : THE RECEPTOR ORGANS
The bodies of all animals, from one-celled organisms to humans, have touch receptor cells all over their surfaces. Any particularly sensitive area is often called an organ of touch, such as the human hand, the mole's nose and the tentacles of the jellyfish. When necessary, touch can be used to substitute for sight. Blind people, for example, 'read' using their sense of touch when they use Braille.
Fish have a special organ along each side of their bodies called the lateral line. The lateral line is able to sense differences in the pressure of water around the fish. This organ helps carnivorous fish to locate their prey and also helps fish detect predators and find sexual partners. It is thought that the lateral line system is responsible for keeping shoals of fish together as they move swiftly through the water.
A few fish have a specialized lateral line system with electrically sensitive organs. These organs are found deep in the body, often in the head of the fish. Sharks, rays and catfish use these organs to detect the weak electric charges produced by their prey. Freshwater eels, however, use the same organ to find and stun their prey.
Eels use electric shocks to stun their prey
The organ acts as an emitter by producing frequent weak electric shocks (300 per second) into the water. These eels can sense whether the electric field is deformed by the presence of another animal. When another animal is detected, the organ acts as a receiver and the eel produces an electric current strong enough to stun its prey.
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